The present invention relates to a valve for internal combustion engines, and more particularly to an intake and/or exhaust valve which passively rotates in operation so as to create an improvement in valve life.
Induction valves, including intake as well as exhaust valves, for internal combustion engines are normally of the poppet type valve. Each such poppet valve includes a valve head adapted to seat against a valve seat in the cylinder head of the engine. The valve reciprocates to control the flow of induction fluid through an intake passage in the cylinder head to a cylinder of the engine during the induction cycle for that cylinder. Normally, the valve head of such a poppet valve is constituted as a body of revolution about an axis and is provided with a stem extending coaxially with this axis. The stem of the poppet valve is reciprocally journaled in a suitable valve stem guide bore provided in the cylinder head. The free end of the stem of the valve normally projects from the cylinder head a suitable distance so that it can be engaged by a suitable actuator device, such as a rocker arm, to effect a reciprocating movement of the poppet valve in an opening direction. A valve return spring is used to effect reciprocating movement of the poppet valve in an opposite or valve closing direction.
In such a conventional type valve, the continual high speed reciprocation of the valve creates a great amount of frictional wear on the valve face and seating surface. Additionally, deposits tend to accumulate upon such surfaces, which can contribute to the frictional wear of such surfaces and/or to a reduction in the operating efficiency of the engine. Accordingly, various ways have been used in the prior art to increase the life of the valves. One such method is that of inducing valve rotation within the guide bore during reciprocation. However, this rotation has been accomplished by mechanical arrangements which are expensive, provide inadequate reliability and are complex.
The present invention is directed to overcoming one or more of the problems as set forth above.
The present invention overcomes the disadvantages described above by providing a valve assembly having a valve member that rotates within a valve guide without the necessity of additional mechanical components.
The valve assembly of the present invention includes a valve guide and a valve member to control the flow of an induction fluid through an intake passage of the cylinder head. The valve guide provides a bore defining a longitudinal axis and includes a helical bore groove. The valve member includes a valve head and a stem having a helical stem groove. The valve member is guided for reciprocal movement within the guide such that the valve head reciprocates between an open and a closed position in relation to a valve seat. The helical bore groove and the helical stem groove interact to impart an axial rotation to the valve member about the longitudinal axis.
The valve guide includes a rifled-like bore and the valve stem includes a helical stem groove of a higher lead. Preferably, the helical stem groove defines a lead approximately 150% the lead of the helical bore groove. A lubricating fluid, as commonly provided to moving parts of an engine, lubricates the interaction of the valve bore and valve stem. The lubricating fluid creates a hydrodynamic film between the valve bore and valve member which, in relation to the interaction of the helical grooves, results in a highly effective axial rotation of the valve member within the valve guide. This axial rotation, although relatively predictable, is sufficiently random such that a frictional wear area is unlikely to occur on a discrete location of the valve stem or valve guide.
The present invention therefore provides an uncomplicated and inexpensive valve assembly which can be adapted to existing valve assemblies. The reduced frictional wear between the valve guide and valve member results in a high degree of operational reliability and durability.